One of reliability test items of semiconductor devices is an Electro-Static Discharge (ESD) destruction test. Semiconductor devices are guaranteed for electrostatic discharge resistance of a predetermined voltage or higher so as to be resistant to electrostatic discharges of, for example, HBM (Human Body Model), MM (Machine Model), and CDM (Charged Device Model).
The trend in semiconductor devices used for mobile terminals, etc. involves a proceeding toward thin filming of an oxide film of a MOS transistor in a periphery circuit in order to meet the demand of low power consumption, low voltage, and fast speed. Since the destruction voltage resistance of a gate insulating film (oxide film) of a transistor is decreasing in association with this trend, it is demanded to develop an ESD protection circuit operating at a low voltage and a power supply circuit including such an ESD protection circuit.